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NVD / CVE Program· CNA mitre

CVE-2026-26824: libxls through version 1.6.3 contains a use of uninitialized memory vulnerability in the OLE container parser.

MediumCVSS 6.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 26/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.27% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: r-cran-readxl (Debian:14) 1.6.0-1; libxls (openSUSE:Leap 16.0) 1.6.4-bp160.1.1; libxls (openSUSE:Tumbleweed) 1.6.4-1.1.

Low priority for now. Upgrade to r-cran-readxl (Debian:14) 1.6.0-1; libxls (openSUSE:Leap 16.0) 1.6.4-bp160.1.1; libxls (openSUSE:Tumbleweed) 1.6.4-1.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

libxls through version 1.6.3 contains a use of uninitialized memory vulnerability in the OLE container parser. Memory allocated for the Master Sector Allocation Table (MSAT) in read_MSAT() is not fully initialized before being consumed by ole2_validate_sector_chain(), which may result in application crashes or potential information disclosure when processing a crafted XLS file

Published
Jun 3, 2026
Updated
Sep 23, 2026
EPSS
0.2% · 19th percentile

Report tools

JSON

Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
proof of concept
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-26824

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
libxls projectlibxls

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • libxls project libxlsup to 1.6.3 inclusive

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12r-cran-readxlfrom 0—
Debian:14r-cran-readxlbefore 1.6.0-11.6.0-1
openSUSE:Leap 16.0libxlsbefore 1.6.4-bp160.1.11.6.4-bp160.1.1
openSUSE:Tumbleweedlibxlsbefore 1.6.4-1.11.6.4-1.1

Same product

libxls project: all records

Other highest-scoring records for the same primary product.

  • CVE-2017-2910An exploitable Out-of-bounds Write vulnerability exists in the xls_addCell function of libxls 2.0.
    36Monitor
  • CVE-2017-12109An exploitable integer overflow vulnerability exists in the xls_preparseWorkSheet function of libxls 1.4 when handling a MULRK record.
    36Monitor
  • CVE-2017-12108An exploitable integer overflow vulnerability exists in the xls_preparseWorkSheet function of libxls 1.4 when handling a MULBLANK record.
    36Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2023-38855Aug 15, 2023 · Buffer Overflow vulnerability in libxlsv.1.6.2 allows a remote attacker to execute arbitrary code and cause a denial of service via a…
    26Monitor
  • ← EarlierCVE-2023-38856Aug 15, 2023 · Buffer Overflow vulnerability in libxlsv.1.6.2 allows a remote attacker to execute arbitrary code and cause a denial of service via a…
    26Monitor
  • Later →CVE-2026-26825Jun 3, 2026 · A use-of-uninitialized memory vulnerability exists in libxls 1.6.3 when parsing malformed XLS files.
    21Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:r-cran-readxl1.6.0-1 · Debian:14Package registry (OSV)
opensuse:libxls1.6.4-1.1 · openSUSE:TumbleweedPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Not on record for this CVE: EPSS history · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
none
Availability
low · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
None
Availability impact
Low

Weakness class (CWE)

CWE-457 · Use of Uninitialized Variable

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records